Alarm lock



INVENTOR A. LEFEBVR E ALARM LOCK Oct. 12, 1937.

Filed Jan. 14, 1937 WITNESSES M y n 1w A ad Lm Patented Oct. 12, 1937 UNITED STATES PATENT yOFFICE 2 Claims.

'I'his invention relates to alarm locks, an object of the invention being to provide a pin tumbler lock with improved circuit closing means so that when a key is positioned in the lock it 5 will cause the movement of one 0r more pin tumblers to close the circuit and sound the alarm.

It is a well-known fact that many burglaries take place by the burglar having a proper key or a skeleton key to unlock a door or window, and

it is the broad purpose of my invention to provide an alarm lock which when the proper key or any other key is positioned in the lock or an attempt made to position a key in the lock, an alarm will be sounded.

A further object is to provide improved circuit closing means which can be incorporated in the ordinary standard pin tumbler lock, and which will be comparatively simple in construction, eilicient in operation, and strong and durable in use.

With these and other objects in View, the invention consists in certain novel features of construction and combinations and arrangements of parts, all of which will be more fully hereinafter described and pointed out in the claims.

In the accompanying drawing- Fig. l is a view in longitudinal section through a pin tumbler lock equipped with my improved circuit closing means;

Fig. 2 is a View in transverse section on the line 2-2 of Fig. l, and

Fig. 3 is a view similar to Fig. 2 illustrating a modification.

I0 represents the casing, II the barrel, and I2 the pin tumblers with which locks of this character are ordinarily equipped. I3 indicates the springs on top of the pin tumblers held in the pin bores I4 by the ordinary covering plate I5, and I6 is the ordinary key to operate the lock.

Around the lock I secure a supporting clamp Il securely held on the lock by means of a screw I8 and a nut I9. The screw i8 also functions as a terminal for the connection of a wire 20, which is grounded as shown at 2|. In the clamp Il a tubular member 22 of insulation is located, and

a Washer 23, also of insulation, is clamped against the end of the tubular member 23 by means of a screw 24 and a nut 25. On this tubular member 22 an electric contact 26 is secured and projects above the lock casing, and a strip El of insulation is located between the contact 26 and the clamp Il to prevent grounding of the circuit. This contact 26 is electrically connected to a wire 23 which in turn is connected to a battery or other source of electricity 29, the other side of the battery having a wire 30 connected thereto and (Cl. 20o-44) grounded as shown at 3I. Included in the circuit with this Wire 30, is a bell or other signal 32, and a manually operable switch 33 is located at any convenient point in the circuit.

In two of the bores I4 I provide circuit closing pins 34 which have heads 35 at their lower ends resting on the pin tumblers I2. These circuit closing pins extend through the plate I5 and through openings 36 in the covering plate I5 and through openings 3l in the clamp I'l. The upper l0 ends of these circuit closing pins 34 are normally spaced from the contact 26 but when the key I6 is positioned in the barrel of the lock it Will cause the pin tumblers to be lifted and lift the circuit closing pins 34 to engage the contact 26 and close l5 the circuit and sound the alarm. While I have illustrated two of these contact pins, it is to be understood, of course, that the invention is not limited to the particular number as I may employ one or more of these pins as desired. 20

The above described construction illustrated specically in Figs. 1 and 2, is especially designed where the lock is to be used in a wooden door, but where the lock is to be used in a metal door, it is ydesirable to cushion the contact pins so as to prevent any possibility of the pins forcing the contact away from the lock to engage the metal door and short-circuit the alarm. This idea is illustrated in Fig. 3 of the drawing, where it will be noted that instead of providing the longer gn springs as illustrated in Figs. 1 and 2 of the drawing, I cut these springs in half and locate one short spring 38 directly on top of the pin tumblers I2 and enclose the same in a cup 39. The circuit closing pin 40, corresponding to the :17 circuit closing pin 34 above described, has its headed end in the cup and against which the spring 38 operates. The other short spring 4I is located between the cup 39 and the covering plate I5. Thus it will be seen that the circuit ,zo closing pin 40 has a certain amount of cushioning in that it may move in 4the cup against the action of the spring' and preventing any possibility of forcing the contact 26 against the metal of the door. 45

While I have illustrated and described what I believe to be preferred embodiments of my invention, it is obvious that various slight changes may be made with regard to the form and arrangement of parts without departing from my invention, 50 and hence I do not limit myself to the precise details set forth but consider myself at liberty to make such changes and alterations as fairly fall Within the spirit and scope of the claims.

I Claim: 55

Cil

1. The combination with a pin tumbler lock, of a circuit closing pin supported upon and movable by a pin tumbler and projecting outside of the lock, a split clamp around the lock, a screw and nut coupling the end of the clamp, the screw constituting an electric terminal, said circuit closing pin beingin electric contact with the clamp and a contact secured to the clamp and insulated therefrom and located above the lock in position to be engaged by the circuit Closing pin when the pin tumbler is elevated by the insertion of a*A key in the barrel of thelock( 'Y' the cup and projecting above the lock, a head Von Y said pin in the cup against which the lower spring bears, and a contact insulated from'the lock and adapted to be engaged by said circuit closing pin Y when a key is inserted in the lock. Y

ALDE LEFEBVRE. 

